# 14-赋值运算符.py
a = 2
b = 3
sum = 0
# 1、计算总消费
sum = a + b
print(sum)

c = 12
# 2、再次记总账
sum+=12 # 等效于 sum = sum+c
print(sum)

d = 2
sum-=2 # 等效于 sum = sum-2
print(sum)
